1. Check that the paper (media) in the tray is supported. For information on the supported paper weights, sizes, types and print areas see the following links:
   Phaser 840 All about media (supported paper sizes, types, print area and weights)
   Phaser 850 All about media (supported paper sizes, types, print area and weights)
2. By hand, feed a sheet of cardstock (paper) into the preheater to remove any obstructions or paper scraps .
3. Check that the Pick Flag moves freely and is in the down position. See the following link for information on: Checking the Pick Flag.
4. Verify the tray back stop is not loose or missing from all removable paper/media trays. See the following link for information on: Inspecting the paper tray for broken parts.

For additional troubleshooting information on loading the trays, cleaning the rollers, preventing jams and reinstalling the black plastic pick guide see the following links: loading the trays, cleaning the rollers, preventing jams, reinstalling the black plastic pick guide